Recent work in this laboratory has shown that prolonged exposure to low-level microwave radiation (0.5 mW for 8 hrs. at 9 GHz) will induce putatively cumulative teratogenic damage in pupae of the darkling beetle Tenebrio molitor. The work proposed here is to determine (a) whether intermittent exposure to microwave energy during pupation causes like damage, as predicted by our previous results; (b) the power level for putatively thermally induced damage and to examine the distribution of types of damage below the thermal level; and, (c) the influence of microwave frequency in the production of teratogenesis and thereby obtain data to help identify possible mechanisms for the non-thermal effects already observed.